Osteology of Skull and Cervical Spine Flashcards
1
Q
What are the categories of cervical vertebrae?
A
- Typical
- Atypical
2
Q
What does wether a cervical vertebrae is typical or atypical depend on?
A
Their osteological features
3
Q
What are the atypical cervical vertebrae?
A
C1, C2, and C7
4
Q
What is C1 known as?
A
Atlas
5
Q
What shape is C1?
A
Ring shaped
6
Q
What is the function of the atlas?
A
Supports the skull at the atlanto-occipital joint
7
Q
What does the atlas articulate with inferiorly?
A
The second cervical vertebrae
8
Q
What is C2 known as?
A
Axis
9
Q
How does the strength of the axis compare to other cervical vertebrae?
A
It is the strongest of all cervical vertebrae
10
Q
Why is the axis need to be the strongest cervical vertebrae?
A
Because C1, carrying the skull, rotates on it
11
Q
What feature does C2 have?
A
Odontoid process (the dens)
12
Q
Where does the odotoid process project?
A
Superiorly from its body
13
Q
How is the odontoid process held in position?
A
By strong transverse ligament of atlas
14
Q
What is the function of the transverse ligament of the atlas?
A
Prevents horizontal displacement of the atlas, thus stabilises the atlanto-axial joint
15
Q
What is the bony skeleton of the neck formed by?
A
The 7 cervical vertebrae
16
Q
Where do the cervical vertebae lie?
A
Between the skull and the thorax
17
Q
What is found between each vertebrae?
A
An intervertebral disc
18
Q
What is the exception to there being an intervertebral disc between vertebrae?
A
There is no vertebral disc between C1/2
19
Q
Why is there no intervertebral disc between C1/2?
A
Because C1 has no vertebral body
20
Q
How do the cervical vertebrae differ in function to other vertebrae in the body functionally?
A
- They bear less weight than vertebrae in other regions of the body
- Convey a much greater degree of mobility
21
Q
How do cervical vertebrae differ from other vertebrae in the body structurally?
A
- Much smaller
- Have a foramen in each of their transverse processes
- Vertebral foramen is much larger
- Articular surfaces are more horizontally orientated
22
Q
Why do cervical vertebrae have a foramen in each of their transverse processes?
A
Transmit vertebral arteries on their way to supply the back of the brain
23
Q
Which cervical vertebrae doesn’t have transverse foramen?
A
C7
24
Q
Why is the vertebral foramen of cervical vertebrae much larger than other vertebrae in the body?
A
Accommodate much thicker cervical spinal cord
25
What happens to the vertebral foramen the more caudal it goes?
It gets smaller
26
Why does the vertebral foramen get smaller as it runs more caudally?
Because the spinal cord it transmits gets thinner, as more and more nerves leave the spinal cord to innervate various structures
27
What is the result of the articular surfaces of cervical vertebrae being more horizontally orientated than in other vertebrae?
They can dislocate or 'slip off' at much less force than is required for them to fracture
28
What is the skull?
The collective term referring to the complete skeleton of the head
29
What does the skull include?
* Cranium
* Mandible
30
What can the cranium be further subdivided into?
* Neurocranium
* Viscerocranium
31
What is the neurocranium?
The bones forming a protective box around the brain
32
What is the viscerocranium?
Bones forming facial skeleton
33
What does the neurocranium consist of?
* Calvaria
* Cranial floor
34
What is the calvaria?
The skull, or cranial, cap
35
What is the lower limit of the calvaria?
It has no lower limit to it as such
36
What do the bones of the calvaria consist of?
Two layers of bones, seperated by a layer of spongy bone
37
What is the layer of spongy bone in the calvaria known as?
Diploe
38
What is true of the innermost layer of the calvaria in adults?
It is particularly brittle
39
What is the purpose of the trilaminar arrangement of bone in the calvaria?
It conveys protective stength, without adding significant weight
40
What is the thinnest part of the calvaria?
The pterion
41
Where does the pterion lie?
On the lateral aspect of the skull
42
What is between the large, flat bones forming the calvaria?
Sutures
43
What are sutures?
Serrated, immobile joints of strong fibrous tissue
44
What are the names of the sutures?
* Coronal
* Sagittal
* Lamboid
45
What is the clinical relevance of sutures?
* Interlocking nature of these joints makes it very different or bones forming the joint to dislocate
* As we age, suture lines begin to ossify
46
What is the cranial floor divided into?
Three areas, or fossa
47
What are the areas of the cranial floor?
* Anterior
* Middle
* Posterior
48
What is found in the cranial floor?
A number of foramina (holes)
49
What is the function of the holes in the cranial floor?
Allow for passage of anatomical structures between extra- and intra-cranial compartments
50
What structures pass through the foramen in the cranial floor?
* Cranial nerves
* Blood vessels
51
What is the clinical relevance of the large number of foramina in the cranial floor?
Make the cranial floor vulnerable to fracture
52
When can the vertebral floor fracture?
When significant force is transmitted through the skull base
53
What is the viscerocranium formed by?
* Bones enclosing the orbits
* Nasal cavity
* Oral cavity
* Paranasal sinuses
* Maxillae
* Mandible
54
What is the maxillae?
The upper jaw
55
What is the mandible?
The lower jaw
56
What does the jaw house?
The teeth
57
What are the main features of the anterior aspect of the skull?
* Frontal bones
* Zygomatic bones
* Orbits
* Nasal region
* Maxillae
* Mandible
58
What do the frontal bones form?
Skeleton of forehead
59
What does the frontal bone articulate with?
* Nasal bones
* Zygomatic bones
* Lacrimal bones
* Ethmoid bones
* Sphenoid bones
60
What do the frontal bones form?
* Roof of orbit
* Part of floor of cranial cavity
61
What are the zygomatic bones?
Cheek bones
62
Where do the zygomatic bones lie?
On the inferolateral sides of orbits
63
What do the zygomatic bones articulate with?
* Frontal bone
* Sphenoidal bone
* Temporal bone
* Maxillae
64
What does the maxillae constitute?
The greater part of the upper facial skeleton
65
What is the maxillae fixed to?
Cranial base
66
Why is the mandible moveable?
Because it articulates with the cranial base at the temporomandibular joint
67
Why is the temporomandibular joint special?
It is the only moveable joint of the skull
68
What is found just above the orbital margin?
Supraciliary arch
69
What is the supraciliary arch?
A sharp bony ridge
70
Will slight dislocation of the cervical vertebrae damage the spinal cord?
It may or may not
71
Why may slight dislocation of the cervical vertebrae not damage the spinal cord?
Due to large vertebral canal in cervical region
72
What may significant dislocation of the cervical vertebrae cause?
Serious injuries to the spinal cord
73
What serious injuries to the spinal cord can be caused by significant dislocation of the cervical vertebrae?
* Partial paralysis
* Complete paralysis
* Death
74
What are the most common sites of cervical spine injuries?
* C1/2
* C6
* C7
75
Where do most severe *(often fatal)* spinal injuries occur?
In the upper part of the spine *(C1-4)*
76
What does damage to the upper part of the spine lead to?
* Quadriplegia
* Cessation of respiratory movements
77
When may a hyperflexion of the cervical spine injury occur?
During head on collision
78
What do hyperflexion injuries of cervical spine tend to involve?
Lower part of cervical spine
79
What can hyperflexion injuries of the cervical spine lead to?
* Crush factors of the vertebral body
* Rupture of supraspinous ligament
* Rupture of lower cervical intervertebral discs
80
Give an example of a crush fracture of the cervical spine?
Cervical wedge fracture
81
Is a cervical wedge fracture stable?
May be, if just one vertebra is involved
82
How will a cervical wedge fracture present on x-ray?
Loss of height of vertebral body
83
What are crush fractures of the vertebral body associated with?
Spinal degenerative disease
84
Give an example of a spinal degenerative disease?
Osteoporosis
85
What is the effect of the rupture of the supraspinous ligament?
Makes bony spine unstable
86
What cervical intervertebral discs can rupture?
* C5/6
* C6/7
87
What complication can rupture of the lower cervical spinal discs cause?
May cause compression of spinal nerve roots C6 and C7
88
What are hyperextension injuries of the neck associated with?
Rear-end vehile collision
89
What do hyperextension injuries of the neck most commonly affect?
Upper cervical spine
90
What can hyperextension injuries of the neck result in?
* Vertebral fracture
* Disc prolapse
* Cervical spinous process or odontoid process fracture
* Tearing of anterior longitudinal ligament
* Kinking of posterior longitudinal ligament
91
Where may hyperextension injuries of the neck cause kinking of the posterior longitudinal ligament?
In the degenerative spine
92
What is the protective function of car seat head rests?
They act to minimise the range of hyperextension that can occur at the neck
93
What is a Hangmans Fracture?
A type of injury that can occur caused by hyperextension of the neck
94
When may a Hangmans Fracture occur?
During judicial hanging, *not suicidal hanging*
95
What is the cause of death in suicidal hanging?
Asphyxiation
96
What happens in a Hangmans Fracture?
Bilateral fracture of posterior arch of C2, and disruption of C2-3 junction
97
Is a hangmans fracture stable?
No
98
What is the result of a Hangmans Fracture being unstable?
There is a risk of C2 displacement and spinal cord damage
99
What needs to be done when someone presents with a Hangmans Fracture?
MRA
100
Give an example of how an axial load injury through the head and neck may occur?
Falling onto head from height
101
What may an axial load injury through the head and neck cause?
Jeffersons fracture
102
What is a Jeffersons fracture?
A burst fracture of C1
103
What happens in a Jeffersons fracture?
Combination of anterior and posterior arch fractures
104
Is a Jeffersons fracture unstable?
It can be
105
What may be neccessary if a Jeffersons fracture is unstable?
External fixation
106
Why must patients presenting with a suspected neck injury be managed carefully?
Avoid (further) damage to the cervical spinal cord
107
Do all neck injuries or cervical fractures cause damage to the spinal cord?
No
108
What should happen to **any** patient with significant mechanism for neck injury?
They should have full in-line spinal immobilisation
109
Why should **all** patients with significant mechanism for spinal injury have full in-line spinal immobilisation?
Due to the potentially catastrophic neurological consequences should spinal injury occur
110
What does full in-line spinal immobilisation include?
Immobilisation of the cervical spine with;
* Appropriately sized semi-rigid collar
* Head blocks
* Tape
And rest of patients spine immoblised on a spinal board
111
When is immobilisation no longer required following a spinal injury?
When the cervical spine has been 'cleared'
112
When can the cervical spine be 'cleared' after injury?
When the patient is determined to be at minimal risk for spinal injury
113
What does the clearing of a C-spine follow?
Thorough clinical examination
114
What is the clearing of a C-spine based on?
Specific criteria, *e.g. Canadian C-spine rules*
115
What should be done if any doubt remains about possibility of spinal injury, or risk to spine, and the C-spine cannot be cleared confidently by clinical examination?
Radiological examinations undertaken
116
What radiological examinations can be undetaken to clear a C-spine?
* Plain radiography, *involving 3 views of the cervical spine*
* CT
117
When is an x-ray used as the radiological examination to clear C-spine?
In paediatrics
118
Why are x-rays used to clear the C-spine in paediatrics?
Because don't want radiation around structures of the neck, *e.g. the thymus*
119
What would happen if a fracture or other injury was identified on radiological imaging of the C-spine?
Further management would depend on the type of injury found
120
What are the facet joints of the vertebral arches (**zygopophyseal joints**) close to?
Intervertebral foramina
121
What emerges through the intervertebral foramina?
Spinal nerves
122
What happens if the zygapophyseal joints are affected by osteoarthritis?
Intervertebral foramen can narrow
123
What can age related changes in intervertebral discs cause?
Cause the discs to bulge, narrowing the intervertebral foramen
124
What can narrowing of the intervertebral foramen cause?
Compression of the spinal nerve exiting at that vertebral level
125
Give two pathologies resulting from narrowing of the intervertebral foramen?
* Cervical spondylotic myelopathy
* Cervical spondylotic radiculopathy
126
What happens in cervical spondylotic myelopathy?
Spinal cord compression
127
What does cervical spondylotic myelopathy lead to?
* Loss of function
* Often loss of fine motor skills in upper limbs
128
What happens in cervical spondylotic radiuclopathy?
Nerve root impingement
129
What does cervical spondylotic radiculopathy lead to?
Dermatomal arm pain, *with or without mild weakness and sensory loss*
130
What can osteoarthritis of the C-spine lead to?
Cervical spondylosis
131
In laymans terms, what is cervical spondylosis?
'Wear-and-tear' of C-spine vertebrae
132
Who does cervical spondylosis affect?
Older population
133
How common is cervical spondylosis?
Very common
134
What are the features of cervical spondylosis?
* Osteophytes
* Facet joint hypertrophy
* Disc herniation
* Disc space narrowing
* Sclerosis of end plates
135
What are osteopytes?
Bony spurs
136
What may severe blows to the skull result in?
* Local depression and splintering of bone
* Series of linear fractures radiating away from the initial point of injury
137
What severe trauma to the skull may result in fractures?
Impact injuries or blows
138
What complications can arise from skull fractures?
Can damage underlying brain and/or blood vessels
139
What does bleeding into the cranial cavity cause?
Haematoma
140
What are the types of intracranial haematoma?
* Epidural
* Extradural
* Subdural
141
Where does an extradural haematoma occur?
Between skull periosteum and outermost meningeal layer
142
What is the outermost meningeal layer?
Dura mater
143
What happens in an extradural haematoma?
It bleeds into the skull at high pressure, which can press on the brain, *causing abnormal neurology*
144
Wha is an extradural haematoma associated with?
Trauma and skull fracture
145
What is it important to do when a patient presents with a head injury?
* Examine head and any wounds thoroughly
* Undertake neurological assessment
146
What should be determined in a neurological assessment?
If there is evidence, or risk of, brain injury
147
What should be done when there is clinical suspicion of intracranial haemorrhage?
* CT imaging of head
* Consideration to possibility of C-spine injury
148
What is a basilar skull fracture?
Fracture through cranial floor
149
When can a basilar skull fracture occur?
If significant force is transmitted through the vertebral column
150
Why can a basilar skull fracture occur if significant force is transmitted through vertebral column?
Because base of skull is connected to vertebral column
151
How does a basilar skull fracture present?
* Battle's sign
* 'Raccoon' eyes
* Haemotympanum
* Meningeal tears
* Cranial nerve palsies
152
What is Battle's sign?
Bruising over mastoid process
153
What is 'Raccoon' eyes?
Bruising around both eyes
154
What is haemotympanum?
Blood behind ear drum
155
What results from meningeal tears?
Bleeding and/or CSF leakage from;
* Ear
* Nose
156
What is is called when CSF leaks from the ears?
CSF otorrhea
157
What is it called when CSF leaks from the nose?
CSF rhinorrhea
158
Why may a basilar skull fracture lead to cranial nerve palsies?
As cranial nerves run along base of skull in many cases
159
What is there a risk of in basilar skull fractures?
* Meningtis
* Need for neurosurgical intervention
160
How common are basilar skull fractures?
Uncommon, *less than 5% of skull fractures*
161
What does a fracture at the pterion risk?
Injuring the middle meningeal artery (anterior branch)
162
Why does a fracture at the pterion risk damaging the middle mengingeal artery?
As it lies immediately beneath the bone
163
What will bleeding from the anterior branch of the middle meningeal artery cause?
Extradural haematoma
164
What happens in an extradural haematoma from the anterior branch of the middle meningeal artery?
Blood accumulates between the periosteal layer of dura mater and the bone, *exerting pressure on underlying brain*
165
How are injuries to the facial skeleton caused?
* Road traffic collisions
* Fights
* Falls
166
What do the most common facial fractures involve?
* Nose
* Zygomatic bone
* Mandible
167
Why are fractures of the nasal bone common?
Because of the prominence of the nose
168
What does a hard blow to the lower jaw often result in?
Fracture of the neck of the mandible and its body
169
What may fracture of the mandible be associated with?
Dislocation of the temporomandibular joint
170
What is required to fracture the maxillary and frontal bones?
Significant force
